Aerial shoots to 50 cm, 4 mm diam. at base. Appendages 0.7--2.5 mm (sterile), 1--1.5 mm (fertile). Synangia yellowish to greenish yellow, 2--3 mm wide. Low to mesic woods, thickets, swamps, hammocks, rocky slopes; 0--50 m (1100 m in Ariz.); Ala., Ariz., Fla., Ga., La., Miss., S.C., Tex.; Mexico; West Indies in the Antilles; Central America; South America; tropical Asia; tropical Africa. Reports of Psilotum nudum in New Mexico and in west Texas remain unverified. A wide range of chromosome numbers on material outside the flora has been reported for this species: n =ca.46--56, 104, 210. Most counts, however, are based on n =52 (reviewed in P.J. Brownsey and J.D. Lovis 1987). No count is available from North American material. Psilotum nudum occurs as a minor weed in greenhouses. Many horticultural forms---including one without appendages and with terminal synangia (A.S. Rouffa 1971)---are grown, especially in Japan.

PLANT: terrestrial in AZ. STEMS dichotomously branched to 20 cm, 3-angled, 4 mm in diameter. LEAVES: absent or scalelike, less than 1 mm long. SYNANGIA: SYNANGIA yellowish to greenish yellow, 2-3 mm wide. NOTES: Rocky slopes: Santa Cruz Co.; ca. 1100 m; Jan-Dec; AL, FL, GA, LA, MS, SC, TX; Mex., C. and S. Amer., W. Ind., and Old World Tropics. REFERENCES: Raul Gutierrez Jr., 2007, Vascular Plants of Arizona: Psilotaceae. CANOTIA 3 (2): 32-34.

General: Terrestrial plant, sometimes epiphytic, aerial shoots clumped, to 50 cm, 4 mm diameter at base, simple below, dichotomously branched above, often 3 ridged. Leaves: More appendages than leaves, minute and bractlike, 0.7-2.5 mm for the sterile ones and 1-1.5 mm for fertile ones, borne an the upper part of the ridges of the aerial shoots. Sporangia: Synangia globose, obscurely 3-lobed, yellowish to greenish yellow, 2-3 mm wide. Ecology: Found in moist habits, under rocks, on rocky slopes, and in thickets from sea level to 4,000 ft (1219 m). Notes: Collection in SAGU is from beneath a rock up Chiminea Canyon. Etymology: Psilotum is from the Greek psilos naked, while nudum means bare or naked. Sources: FNA 1994